我有一门课叫问题(复数)。在这个类中有一个名为Question(单数)的枚举,看起来像这样。

public enum Question
{
    Role = 2,
    ProjectFunding = 3,
    TotalEmployee = 4,
    NumberOfServers = 5,
    TopBusinessConcern = 6
}

在Questions类中,我有一个get(intfoo)函数,它为该foo返回Questions对象。有没有一种简单的方法可以从枚举中获取整数值,这样我就可以执行类似于Questions.get(Questions.Role)的操作?


当前回答

由于枚举可以用多个基元类型声明,因此可以使用泛型扩展方法来转换任何枚举类型。

enum Box
{
    HEIGHT,
    WIDTH,
    DEPTH
}

public static void UseEnum()
{
    int height = Box.HEIGHT.GetEnumValue<int>();
    int width = Box.WIDTH.GetEnumValue<int>();
    int depth = Box.DEPTH.GetEnumValue<int>();
}

public static T GetEnumValue<T>(this object e) => (T)e;

其他回答

在一个相关的注释中,如果你想从System.Enum中获取int值,那么在这里给出e:

Enum e = Question.Role;

您可以使用:

int i = Convert.ToInt32(e);
int i = (int)(object)e;
int i = (int)Enum.Parse(e.GetType(), e.ToString());
int i = (int)Enum.ToObject(e.GetType(), e);

最后两个很难看。我更喜欢第一个。

为了确保枚举值存在,然后解析它,还可以执行以下操作。

// Fake Day of Week
string strDOWFake = "SuperDay";

// Real Day of Week
string strDOWReal = "Friday";

// Will hold which ever is the real DOW.
DayOfWeek enmDOW;

// See if fake DOW is defined in the DayOfWeek enumeration.
if (Enum.IsDefined(typeof(DayOfWeek), strDOWFake))
{
    // This will never be reached since "SuperDay"
    // doesn't exist in the DayOfWeek enumeration.
    enmDOW = (DayOfWeek)Enum.Parse(typeof(DayOfWeek), strDOWFake);
}
// See if real DOW is defined in the DayOfWeek enumeration.
else if (Enum.IsDefined(typeof(DayOfWeek), strDOWReal))
{
    // This will parse the string into it's corresponding DOW enum object.
    enmDOW = (DayOfWeek)Enum.Parse(typeof(DayOfWeek), strDOWReal);
}

// Can now use the DOW enum object.
Console.Write("Today is " + enmDOW.ToString() + ".");

我想建议“从枚举中获取‘int’值”的示例是

public enum Sample
{
    Book = 1, 
    Pen = 2, 
    Pencil = 3
}

int answer = (int)Sample.Book;

现在答案是1。

尝试使用此方法,而不是将enum转换为int:

public static class ReturnType
{
    public static readonly int Success = 1;
    public static readonly int Duplicate = 2;
    public static readonly int Error = -1;        
}
Question question = Question.Role;
int value = (int) question;

将导致值==2。